1 | // License: GPL. For details, see LICENSE file.
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2 | package org.openstreetmap.josm.io;
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3 |
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4 | import java.io.File;
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5 | import java.io.IOException;
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6 | import java.nio.file.FileSystems;
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7 | import java.nio.file.Path;
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8 | import java.nio.file.StandardWatchEventKinds;
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9 | import java.nio.file.WatchEvent;
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10 | import java.nio.file.WatchEvent.Kind;
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11 | import java.nio.file.WatchKey;
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12 | import java.nio.file.WatchService;
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13 | import java.util.Collections;
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14 | import java.util.HashMap;
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15 | import java.util.Map;
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16 |
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17 | import org.openstreetmap.josm.Main;
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18 | import org.openstreetmap.josm.gui.mappaint.MapPaintStyles.MapPaintStyleLoader;
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19 | import org.openstreetmap.josm.gui.mappaint.StyleSource;
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20 | import org.openstreetmap.josm.tools.CheckParameterUtil;
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21 |
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22 | /**
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23 | * Background thread that monitors certain files and perform relevant actions when they change.
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24 | * @since 7185
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25 | */
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26 | public class FileWatcher {
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27 |
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28 | private WatchService watcher;
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29 |
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30 | private final Map<Path, StyleSource> styleMap = new HashMap<>();
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31 |
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32 | /**
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33 | * Constructs a new {@code FileWatcher}.
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34 | */
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35 | public FileWatcher() {
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36 | try {
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37 | watcher = FileSystems.getDefault().newWatchService();
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38 | new Thread(new Runnable() {
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39 | @Override
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40 | public void run() {
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41 | processEvents();
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42 | }
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43 | }, "File Watcher").start();
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44 | } catch (IOException e) {
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45 | Main.error(e);
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46 | }
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47 | }
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48 |
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49 | /**
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50 | * Registers a map paint style for local file changes, allowing dynamic reloading.
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51 | * @param style The style to watch
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52 | * @throws IllegalArgumentException if {@code style} is null or if it does not provide a local file
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53 | * @throws IllegalStateException if the watcher service failed to start
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54 | * @throws IOException if an I/O error occurs
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55 | */
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56 | public void registerStyleSource(StyleSource style) throws IOException {
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57 | CheckParameterUtil.ensureParameterNotNull(style, "style");
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58 | if (watcher == null) {
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59 | throw new IllegalStateException("File watcher is not available");
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60 | }
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61 | CachedFile cf = style.getCachedFile();
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62 | // Get underlying file
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63 | File file = cf.getFile();
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64 | if (file == null) {
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65 | throw new IllegalArgumentException("Style "+style+" does not have a local file");
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66 | }
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67 | // Get parent directory as WatchService allows only to monitor directories, not single files
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68 | File dir = file.getParentFile();
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69 | if (dir == null) {
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70 | throw new IllegalArgumentException("Style "+style+" does not have a parent directory");
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71 | }
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72 | synchronized(this) {
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73 | // Register directory. Can be called several times for a same directory without problem
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74 | // (it returns the same key so it should not send events several times)
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75 | dir.toPath().register(watcher, StandardWatchEventKinds.ENTRY_MODIFY, StandardWatchEventKinds.ENTRY_CREATE);
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76 | styleMap.put(file.toPath(), style);
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77 | }
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78 | }
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79 |
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80 | /**
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81 | * Process all events for the key queued to the watcher.
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82 | */
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83 | private void processEvents() {
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84 | if (Main.isDebugEnabled()) {
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85 | Main.debug("File watcher thread started");
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86 | }
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87 | while (true) {
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88 |
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89 | // wait for key to be signaled
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90 | WatchKey key;
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91 | try {
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92 | key = watcher.take();
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93 | } catch (InterruptedException x) {
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94 | return;
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95 | }
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96 |
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97 | for (WatchEvent<?> event: key.pollEvents()) {
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98 | Kind<?> kind = event.kind();
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99 |
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100 | if (StandardWatchEventKinds.OVERFLOW.equals(kind)) {
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101 | continue;
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102 | }
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103 |
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104 | // The filename is the context of the event.
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105 | @SuppressWarnings("unchecked")
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106 | WatchEvent<Path> ev = (WatchEvent<Path>)event;
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107 | Path filename = ev.context();
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108 | if (filename == null) {
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109 | continue;
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110 | }
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111 |
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112 | // Only way to get full path (http://stackoverflow.com/a/7802029/2257172)
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113 | Path fullPath = ((Path)key.watchable()).resolve(filename);
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114 |
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115 | synchronized(this) {
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116 | StyleSource style = styleMap.get(fullPath);
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117 | if (style != null) {
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118 | Main.info("Map style "+style.getDisplayString()+" has been modified. Reloading style...");
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119 | //style.loadStyleSource();
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120 | Main.worker.submit(new MapPaintStyleLoader(Collections.singleton(style)));
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121 | } else if (Main.isDebugEnabled()) {
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122 | Main.debug("Received "+kind.name()+" event for unregistered file: "+fullPath);
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123 | }
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124 | }
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125 | }
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126 |
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127 | // Reset the key -- this step is critical to receive
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128 | // further watch events. If the key is no longer valid, the directory
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129 | // is inaccessible so exit the loop.
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130 | if (!key.reset()) {
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131 | break;
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132 | }
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133 | }
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134 | }
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135 | }
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